1. Field of Invention
The field of invention relates generally to vias and, more specifically, relates to a method and apparatus to provide a via with an increased via contact area.
2. Background Information
Semiconductor dies are typically encased in a shell or package prior to installation in microelectronic devices. The package makes the die easier to handle and protects the die from dust, dirt, and other contaminants. The package usually has leads or contact pads that are soldered to a printed circuit board (PCB). With its leads attached to the PCB, the package acts as an interface between the die and the PCB.
Generally, a die includes dielectric layers attached to a semiconductor support layer. Attached to the dielectric layers are metal layers. In some dies, a via is formed in the semiconductor support and dielectric layers to connect the metal layers to components outside of the die.
In constructing a die package, the diameter of the vias is usually kept to a minimum in order to help reduce electrical interconnect pitch. Electrical interconnect pitch (e.g., bump pitch) is the distance between the center of two electrical interconnects on a die package. In a die package, a via connects to an electrical interconnect which supplies electrical connection out of the package through bumps, pins, leads or other electrical connective items. Smaller diameter vias allow the vias to be placed closer together, and subsequently, reduce the electrical interconnect pitch. A smaller pitch leads to smaller die packages.
However, difficulties arise when a via with a small diameter is connected to a metal layer of a die. The small diameter of the via creates adhesion problems and may result in de-lamination of the via and the metal layer. Also, a connection with a small diameter via may result in undesired levels of electrical resistance in the connection between the via and the metal layer.